This proposal is an application for the continuation of Public Health Service Grant #HL-11119. Its purpose is to make available a common amino acid analyzer and sequencer operation for eight research groups in the Departments of Biochemistry and Molecular Biology and Biological Sciences, by providing support for an operator and the supplies and maintenance for the available equipment. The present research projects dependent on these facilities include the mechanisms of enzyme catalysis (M. Bender); the structure of lactate dehydrogenase- X (E. Goldberg); the comparative biochemistry of oxygen-carrying proteins (I. M. Klotz); the structure and function of photoreceptor complexes in photosynthesis (P. Loach); the calcium dependent unmasking of active center cysteine during activation of fibrin stabilizing factor (L. Lorand); the mitochondrial membrane metabolic role of cytochrome c (E. Margoliash); the biosynthesis of bacterial cell wall components (F. C. Neuhaus); and the structure and function of delta-aminolevulinic acid dehydratase (D. Shemin). These studies are supported by the Public Health Service and the continued existence of a joint amino acid analysis and sequencer operation is the most economical way of providing for their prosecution while obviating duplication of efforts and its resultant inefficiency.